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Ground effect recording

Subject: Ground effect recording
From: "Rich Peet" <>
Date: Wed, 03 Sep 2003 20:58:51 -0000
subject was: RFI:Microphone for recording 360  degrees of sound

Our posts on not putting your mic on the ground was related to 360 
degree ambient recordings.  That should not have been interpreted to 
mean don't ever put your mic on the ground.

Further examples of when to use ground recording would be appreciated 
but here are a couple examples of when to use a mic on the ground.

1. The grouse recording I posted within the last month was recorded 
on the ground.  Setup was made as close to where the bird was 
displaying and I was confident my recording would be made of these 
very low frequencies at a close distance.  By putting the mic on the 
ground I improved the overall signal to noise ratio.

2. The mud flats recording I also posted within the last month was 
made with the mic about 4" off the mud.  This was a pot hole where 
the targets were suppose to be standing in the mud.  Once again set 
to reduce ambient noise and pick up those targets in the mud.  The 
first UFO talked about in this post was best guessed as a Mallard 
Duck in glide over the flats.  The second UFO was likely a sonic boom 
and still could have been those aliens kicking in the warp drive.

3. Ground hillside or bank recordings.  The ground can be used to 
make an omni mic directional or simply to minimize background noise 
off in one direction.

4. Maximize bass frequencies within a sound?  I don't have a good 
example yet but could see it working in theory.

5. Give an illusion of a 10' cricket or 4' mosquito.  I have some 
great 6' killer flys that sound like they carry their prey off at the 
speed of light.

6. Others?

Rich Peet

--- In  Walter Knapp <> 
> Rich Peet wrote:
> > Doug?  I thought you were the guy that recommended step ladders 
> > better sound?
> > 
> > Don't put your mic on the ground.  At least carry a cable tie and 
> > it to the twig of a bush at 5'.  The end result of putting the 
mic on 
> > the ground for bird song frequencies is to cut the range of your 
> > to about 30% of the distance compared to 5'.
> I definitely agree. In the 70's when I worked as a environmental 
> consultant I did some informal tests with our calibrated sound 
> measurement system because we had a job that involved sound 
> in the woods.
> This was in fairly open woods in the Pacific NW. Underbrush was 
about 4' 
> high, above that height you could see quite a ways through the tree 
> The difference between 4' and 1' off the ground varied depending on 
> sound source direction and cover. But it was rarely less than 5dBA 
> at 1', and sometimes the drop was as much as 15dBA. Laying the mic 
> the ground gave even greater drop.
> I'd say get your mic at least as high as the underbrush if 
> Above 4' I found less variation, even when the brush was higher 
than that.
> BTW, I'm one of the ones experimenting with tall stands. My tall 
> will get a mic up to about 17'. The sound is different, I'll not 
> better because that depends on what you want. Reverberation seems 
to be 
> less, the sound more open, clearer.
> Often when recording with the Telinga I'll hold it at arm's length 
> my head for a slight improvement in range over head height.
> Walt


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